Alkaloid and processes for producing the same



Patented Dec. 18, 1945 ALKALOID AND PROCESSES FOR monocmo THE SAME Karl Folkers, Plainfield, N. J., and John Shavel,

, Jr., Glendale, Long Island, N. Y., assignors to Merck & 00., Inc., Rahway, N. J., a corporation of New Jersey No Drawing. Application April 9, 1941, Serial No. 387,654

8 Claims. (61. 260-236) This invention relates to a new alkaloid from species of Erythrina, and to processes for producing it. I

The alkaloids which applicants and their coworkers have produced for the first time from species of Erythrina cause, physiologically, a potent curare-like action, and certain of them have been found particularly useful for the release of spasms and plastic muscular rigidity in patients with spastic paralysis, and for the modification of the severity of the metrazol convulsions, thereby preventingfractures in the convulsive therapy of the psychoses.

Co-pending application Serial No. 343,854, filed July 3, 1940, discloses the production of certain free, combined, and liberated alkaloids from various species Erythrina.

- In that application, it is disclosed that when seeds or parts of plants of Erythrina species are extracted with water, alcohol, etc. (after first having removed fats), a crude alkaloidal extract is obtained which exhibits a high paralysis potency. When this extract is made slightly alkaline, and is extracted with a solvent which is immiscible in water, such as chloroform, a.

isolated and identified, such as aand perythroidine,- erythramine, erythraline, and erythratine.

" The free alkaloidal fraction may be obtained from the Erythrina species by either the preferred procedure (1. e., direct production of the free fraction) or by the alternative procedure (i. e., production of the free fraction after intermediate isolation of the known, physiologically inert alkaloid, hypaphorine). The "preferred procedure comprises the following general steps, briefly described, particularly as applied to the Se d v(1) Extraction of the seeds to remove fats.

, (2) Extraction of the total alkaloids from the defatted seeds by treatment thereof with a solvent such as methyl or ethyl alcohol.

(3) Distillation of the alcohol solution to dryness and dissolving of the residue in water.

(4) Clarification of the aqueous solution by weakly acidifyingand extracting with petroleum ether, and then with chloroform to remove traces gilfats. This operation must be carried out caresolutions with a weak alkalinizing agent.

(6) Extraction of the weakly or slightly alkalinized aqueous solution with chloroform which removes the free alkaloidal fraction.

In the examples given below, wherever we refer to the preferred method it is intended to indicate that the free alkaloidal fraction has been produced from the Erythrina seeds without prior separation of hypaphorine.

Certain variations may be practiced in carrying out this general process. Thus, for example:

(a) Step 1 may be omitted and th fats taken out at step 4 in the process. This is not entirely satisfactory because the mixture obtained is difiicult to handle.

(b) The extraction at step 2 may be carried out with water, in which case step 3 may be omitted. However, this is not a preferred method because water extracts a large quantity ,of extraneous material and subsequent filtrations or solvent extractions are. thus rendered more dim.- cult.

(c) The alkaloid; hypaphorine, occurs in species of Erythrina and can be removed by acidifying the extract remaining after step 4, concentrating to a. small volume, and refrigerating, whereupon the hypaphorine salt crystallizes out. Th process wherein hypaphorine is removed before the free" fraction, is called the alternative procedure.

I In the examples given below, whenever we refer to the falter-native" procedure, it. is intended to indicate that the free fraction has been produced from the Erythrina seeds after intermediate isolation of hypaphorine.

It was found, as disclosed in the co-pending application Serial No. 343,854, that the Erythrina seeds contain not only the free alkaloidal fraction, but also other alkaloids which have been called "combined alkaloids because they are combined with an acid through an ester linkage. These new combined alkaloids appear to.be esters of sulfo-acetic acid, HOsSCI-IzCOzH, and new alkaloidal molecules. This. is evidenced by the fact that acid or alkaline hydrolysis of the new "combined alkaloids yields two components for each combined alkaloid, the sulfo-acetic acid, and the alkaloidal portion, which has been called the liberated alkaloid.

The said co-pending application discloses the production of the new individual. combined alkaloids, erysothiovine and erysothiopine, as well as the new individual liberated alkaloids,

erysodine, erysopine, erysovine, and erysocine.

We have now produced a new individual liberated alkaloid, erysonine, from the species E. costarz'censis' 'Micheli. Certain variations in it has one methoxy ysis lasting for about one hour.

tracted by the "preferred procedure, for the production of the free alkaloidal fraction. The neutralized aqueous solution remaining (about 600. ml.) after the removal of the "free fraction was hydrolyzed by three successive treatments with hydrochloric acid (pH 2-2.3), each hydrol- It was found that the liberated bases from the three hyor C-methyl group. Since it is soluble in dilute sodium hydroxide, one oxygen atompresumably exists in a phenolic hydroxyl grouD,.-and the third oxygen atom is probably .ina hydroxyl group also. The melting point of erysonine is vdiiiicult to obtain, because it melts with decomposition, and varies with the rate of heating the bath. The

average melting point constant forerysonine,

Erysonine, in aqueous solution containing a slight excess of hydrochloric acid, has been found aqueous hydrochloric to cause the characteristic curare-like action when injected intralymphatically into frogs at a dose of 100 mg. /kg. of frog (calculated as the salt) The hydrolyzed or liberated bases obtained from the samples E. costaricensis Micheli may consist of the new liberated" alkaloid erysonine, as well as certain of the other previously disclosed "liberated alkaloids. In such case, appropriate repeated recrystallization of the total hydrolyzed bases from ethanol yields pure crystalline erysonin. I

The following examples illustrate methods of carrying out the present invention on samples of E. costaricensis Michell, but it is to be understood that the e examples are given by way of illustration and not of limitation.

Example I About 50 gms. of finely powdered seeds 'of- E. costaricensis Micheli (Niehaus 9200) were extracted by the alternative procedure, for the isolation of the free alkaloidal fraction. The 50 ml. of neutralized aqueous solution remaining after the removal of the free fraction, was hydrolyzed by treatment with hydrochloric acid (pH 2-2.3) and refluxing for about one hour. The solution was cooled, and alkalinized with sodium bicarbonate. It was repeatedly extracted with chloroform. The chloroform residue of the tallization.

hydrolysis weighed about 748 mg, and after trituration with 0.6 ml. of ethanol, about 358 mg. of bases of melting point about 180-235" were obtained. A negative color test for ery onine indicated that this liberated alkaloid was not present. The bases were recrystallized four times aqueous hydrochloric acid. This decomposition point was later found to be in the range of 236-239 0., when a melting point determination was made on samples of this product and the product of Example 2, in the same melting point .bat-h. We have given this new alkaloid the name erysonine. It does not give a green color with ferric chloride solution.

Example II About 677 gms. of finely powdered seeds of'E.

costariccnsis Micheli (Niehaus '9364) were exnegative color test for erysopine.

I drolyses each gave a positive color test indicating the presence of the individual liberated alkaloid, erysonine, and they were then combined. After trituration with warm ethanol, about 940 mg. of bases of melting point about 195200 C. were obtained. One recrystallization of these bases from ethanol gave about 440 mg. (A) of melting 'pointabout 233-236 C., which gave a The mother liquor gave about 382 mg. of residue (B) of melting point about 183-485 C. Y

The product (A) was recrystallized five times from'ethanol and gave a. product of constant melting point after the second recrystallization.

As in the case of erysonine from the sample E costaricensz's Micheli (Niehaus 9200) described in Example'I, the melting point, with decomposition, of the product obtained was difficult to check, and its determination was always made against that of a sample from the previous crys- The average constants observed were melting point 236-239 C.;

l=1, 0.2 to 0.5% alkaloid in 0.5% aqueous hydrochloric acid; [al =+272, i=1, about 0.5% a1- kaloid in morpholine. The decomposition point of erysonine from .the sample E. costaricensis Micheli (Niehaus 9200) was in this range when compared with this sample from E. costaricemi: Micheli (Niehaus 9364). The soluble residue (B) wasextracted with ether, and yielded about 210 mg. of insoluble material of melting point about -195 0., which was dissolved in 2% aqueous sodium hydroxide,

and extracted ten times with chloroform. The solvent residue, of melting point about 198-200 C., was recrystallized irom ethanol to yield the individual liberated alkaloid erysodlne, of melting point 200-202 0., [u] =+245 (ethanol).

The base, erysonine, in aqueous solution, may be converted to its salts, by the addition of a. slight excess of the appropriate acid, such as hydrochloric acid, hydrobromic acid, sulfuric acid. and the like. I

Modifications may be made in carrying out the present invention without departing from the spirit and scope thereof, and we are to be limited only by the appended claims.

- 1. A substance selected from the group consist.-

ing of the alkaloid erysonine, which is identical with the alkaloidvhaving the same characteristics obtained from aspecies oterythrina and which has'the empirical formula CuHuNOa and in its substantially pure form has a melting point of about 236-239 and the constant (a) =+285- 288 in 5% aqueous hydrochloric acid and ==+272i in morpholine, and salts of said alkaloid.

2. The alkaloid erysonine, identical with the alkaloid having the same characteristics ob tained from a species of erythrina, which has the empirical formula C17H19NO3, and which in its substantially pure form has a melting point. of about 236-239 0.; and the constant [si s-+285- 3. Salts of the alkaloid erysonine, which is identical with the alkaloid erysonine obtained from species of Erythrina containing said alkaloid, has the empirical formula C1'1H19NO3, and in its substantially pure form has a melting point of about 236-239 0., and the constant [a] =+235 288 in 0.5% aqueous hydrochloric acid and [a] =+270, in morpholine.

4. Hydrohalides of the alkaloid erysonine, which is identical with the alkaloid erysonine obtained from species of Erythrina containing said alkaloid, has the empirical formula C17H19NO3, and in its substantially pure form has a melting point of about 236-239" 0., and the constant [a] =+285-288 in 0.5% aqueous hydrochloric acid, and [a] =-|-272, in morpholine.

5. The hydrochloride of the alkaloid erysonine, which is identical with the alkaloid erysonine obtained from species of Erythrina containing said alkaloid, has the empirical formula C17H19NO3, and in its substantially pure form has a melting point of about 236-239 0., and the constant [a] =+285-288 in 0.5% aqueous hydrochloric acid and [a] =|-272, in morpholine.

6. The hydrobromide of the alkaloid erysonine, which is identical with the alkaloid erysonine obtained from species of Erythrina containing said alkaloid, has the empirical formula CrzHroNOa, and in its substantially pure form has a melting point or about 236-239 0., andthe constant [a] =-|-235288 in 0.5% aqueous hydrochloric acid and =+272, in morpholine.

'7. The process comprising hydrolyzing the "combined alkaloids of E. c staricensis Michell, and repeatedly recrystallizing the "liberated alkaloids thus produced, from ethanol, obtaining the individual "liberated alkaloid erysonine which has the empirical formula C17H19NO3, and in its substantially pure form has a melting oint of about 236-239 0., and the constant [a] =+285288 in 0.5% aqueous hydrochlori acid and [a] =+272, in morpholine.

8. The process comprising hydrolyzing' in acid medium the "combined alkaloids of E. costarzcensis Michell, and repeatedly recrystallizing the liberated alkaloids thus produced, from ethanol, obtaining the individual liberated alkaloid erysonine which has the empirical formula C1'1H19N03, and in its substantially pure form has a melting point of about 236-239 0., and the constant [cr] =+285-288 in 0.5% aqueous hydrochloric acid and [a] =+272, in mor-- pholine.

KARL FOLKERS. JOHN SHAVEL, JR. 

